The invention is directed to from a heat shield.
Heat shields are known, for example for use in thermal fluid flow machines and combustion chambers. Usually, these heat shields consist of a carrier material and a thermal insulation layer which is connected to the carrier material by means of a binder layer. This binder layer is applied in the vacuum plasma process; this limits the size of the processable parts due to the size of the vacuum chamber and makes manufacture more costly. A further problem is that at application temperatures exceeding 900xc2x0 C. the binder layer usually fails and the thermal insulation layer falls off. This leads to a failure of the heat shield.
DE 3327216 A has disclosed a thermal protection layer consisting of a metallic felt which is infiltrated and filled with zirconium oxide by means of CVD. This gives rise to a compact firm thermal protection layer. The metallic felt serves as supporting structure for the zirconium oxide coating. The disadvantage of this protection layer involves the high production costs and the inadequate properties with respect to heat resistance and oxidation resistance, in particular of the supporting structure. Moreover, the thermal protection layer can be cooled only with great difficulties, i.e. by means of large cooling air consumption.
Accordingly, one object of the invention, is to provide, in the case of a heat shield of the above mentioned type, a novel cheap and efficient heat shield.
According to the invention, this is achieved by providing a heat shield, comprising a feltlike material composed of compressed and sintered intermetallic fibers.
Accordingly, the core of the invention is that the heat shield is made from a felt-like material composed of compressed and sintered intermetallic fibers.
The, advantages of the invention can be seen is that as a result of the use of intermetallic fibers, the cooling air required to cool the heat shield can be significantly reduced. The feltlike material based on intermetallic fibers can be used at temperatures exceeding 1000xc2x0 C., since the intermetallic fibers have a high heat resistance, a high oxidation resistance and advantageous thermal conduction properties. Moreover, these properties can be regulated by the selected intermetallic phase in controlled fashion and can be adapted to the respective conditions. As a result of the porosity of the feltlike material, a very efficient cooling consuming little cooling air is made possible.
It is advantageous additionally to apply a thermal insulation layer on the feltlike material. This adheres without special intermediate layers to the feltlike material and additionally reduces the cooling requirement and accordingly increases the efficiency of the heat shield in addition.